"Bizarre" New Dinosaur: Giant Raptor Found in Argentina

Scientists have discovered what they say is a completely unexpected new giant dinosaur that lived 70 million years ago in Argentina.

At 16.5 to 21 feet long (5 to 6.5 meters) long, depending on its tail size, Austroraptor cabazai is among the largest of the slender, carnivorous, two-legged dinosaurs called raptors, said Fernando Novas, the lead researcher behind the discovery.

Novas and colleagues were able to virtually reconstruct Austroraptor's complete skeleton, by using the dinosaur's closest relatives as references, said Novas, who received funding for his work from the National Geographic Society's Committee for Research and Exploration. (The National Geographic Society owns National Geographic News.)

The new raptor, or dromaeosaur, belongs to a South American dromaeosaur group known as the unenlagiines, Novas said.

In contrast to their relatives in the Northern Hemisphere, including the Velociraptors from Jurassic Park, unenlagiines had long, low heads and small conical teeth.

The new raptor represents the "the largest dromaesaurid discovered in the Southern Hemisphere," according to a paper by Novas and colleagues published today in the journal Proceedings of the Royal Society of London.

Seventy million years ago Patagonia was a series of plains crossed by rivers filled with fish and turtles, whose fossils were found alongside Austroraptor, Novas said.

Living in this fertile land alongside duck-billed herbivores such as titanosaurs and hadrosaurs, Austroraptor preyed on larger animals than its smaller relatives, thanks to its increased heft and girth, he said.

Turns History Upside-Down

Because paleontologists have found mostly smaller crow- and turkey-size raptors in South America, the new find turns the evolutionary history of raptors—northern and southern—upside-down, said Novas, who is based out of Museo Argentino de Ciencias Naturales in Buenos Aires.